The invention refers to a device for measuring the concentricity of a projectile with respect to the case body of a cartridge, more particularly of a rifle cartridge.
According to the latest findings confirmed by bench rest firing tests, an eccentricity of the projectile with respect to the case exceeding 0.025 mm will cause a deterioration of the firing precision that increases with the eccentricity. In this context, the eccentricity is defined as the angle between the longitudinal axis of the projectile and the case. Ideally, i.e. in the case of perfect concentricity, this angle is equal to zero.
The reduced precision resulting from the eccentricity not only affects the marksman in bench rest shooting. On the contrary, the various types of ammunition, all those applications are concerned where an absolute precision is an indispensable condition for the marksman, such as precision sports shooting, especially medium or long distance, as well as applications in public or private security or in hunting.
Known apparatus for controlling and correcting the concentricity of a cartridge, i.e. essentially for aligning the projectile with respect to the case, only allow a rudimentary concentricity control and do not take account of the actual position of the cartridge in the cartridge chamber of a firearm.
It is an object of the invention to provide a device allowing the measurement and preferably also the alignment of the projectile of a cartridge in order to achieve an improved firing accuracy.
This is accomplished by a device wherein the device comprises a main body having at least one chamber for the cartridge, the chamber includes means for retaining the cartridge by pressing it against a wall of the chamber such that the cartridge remains rotatable, and an access is provided through which a measuring means is capable of contacting the projectile of the cartridge, such that the concentricity of the projectile with respect to the case body is measurable in rotating of the cartridge. Preferred embodiments are described in the remaining claims.
Accordingly, the device essentially imitates the positioning of a rifle cartridge in the cartridge chamber in order to detect concentricity errors of the projectile of the cartridge with respect to its case. In a preferred embodiment, excessive concentricity errors can be corrected by a correcting device.
According to a preferred embodiment, the device is small and inexpensive in manufacture, thus making it suitable for universal applications and easy transport by the marksman. Most preferably the device is in the form of a hand-held tool.
Other preferred embodiments are defined in the claims.